System having termination for data loading port

ABSTRACT

A subsystem of an avionics system is operated in a first mode for receiving software via a port; and in a second mode in accordance with a circuit that includes a terminator coupled to the port. By using the terminator to convey information regarding a desired configuration for operation in the second mode, communication and wiring is avoided between subsystems of the avionics system for conveying such information. In one implementation, operation in the second mode includes performing a collision avoidance function (e.g., providing a TCAS advisory). Configuration information in accordance with the circuit may specify an arrangement of shared antennas between multiple transponders and/or mode changes related to using an antenna for a collision avoidance function in a hijack mode of operation.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 10/260,241, filed Sep. 30, 2002 by Cyro A. Stone etal., the respective disclosure of which is incorporated by reference inits entirety.

FIELD OF THE INVENTION

Embodiments of the present invention relate to installing software andestablishing a configuration for the operation of electronic equipment.

BACKGROUND OF THE INVENTION

Electronic equipment, especially cockpit avionics, are conventionallydesigned to operate according to parametric values established for aparticular installation. By relying on parametric values that areassociated with variations in installations (e.g., on differentaircraft), the cost of design and qualification of avionics can bespread across many different installations and maintenance costs for apopulation of avionics may be reduced. In a typical installation andconfiguration, tables of alternative parametric values are stored inmemory of a processor of the avionics; and, some external indication isascertained for the selection of values particularly suitable for thecurrent installation.

One technique is to choose a connector that is part of the permanentinstallation of the avionics (e.g., a connection already required forpower, input, or output signals), reserve contacts in the connector forshort circuits, define a code for the shorts, opens, and/or resistancebetween reserved contacts of that connector, and associate the code witha table of parametric values. In operation, the processor readsinterface circuits that provide the code, uses the code as an index intothe table, reads the parametric values from the table, and establishes,in accordance with the parameters, any operational criteria, such as,power conditioning, circuit functions, initial conditions, modes ofoperation, use of resources, identifications, limit conditions, andbranch conditions. Giving effect to various parametric values mayrequire switching circuitry for routing signals in alternate ways.

Avionics may be designed to permit the in situ installation of newsoftware for use by the avionics. In a conventional arrangement, theavionics may have an interface connector (e.g., on a front or rearpanel) for data communication signals used to accept the new softwarewhen on the ground or otherwise not in service. In situ installation ofsoftware avoids the expense of removing the avionics from some or all ofits permanent installation (e.g., releasing mechanical restraints,extending circuit assemblies out of the position used in flight,disconnecting cables). Unfortunately, in situ installation of softwareis expensive in that it requires access to skilled personnel andequipment capable of providing the digital communication signals fortransferring the software from such equipment to the avionics.

Without new methods for configuring avionics, the installation andmaintenance of avionics will continue to be limited

SUMMARY OF THE INVENTION

A method for operating a subsystem of an avionics system includes in anyorder, receiving, in a first mode of operation, software via a port; andoperating, in a second mode of operation, in accordance with a circuitthat includes a terminator coupled to the port.

By using the terminator to convey information regarding a desiredconfiguration (e.g., operation in the second mode), communication andwiring is avoided between subsystems of the avionics system forconveying such information.

In one implementation, operation in the second mode includes performinga collision avoidance function (e.g., providing a TCAS advisory). Such amethod may further include using an antenna for a collision avoidancefunction in a hijack mode of operation in accordance with the circuit.

In yet another implementation, operation in the second mode includes ahijack mode of operation.

The port, in another implementation, is part of the front panel of thesubsystem, for example, a front panel receptacle used for in situinstallation of software and for termination as discussed above. Thefront panel receptacle is connected to a terminator that completes acircuit of the subsystem. The circuit establishes a configuration of theinstalled software (e.g., implements a switching function, or provides avalue for a parameter or variable). The circuit of the subsystem mayincorporate the contacts of the receptacle to perform any modificationof circuit functions (e.g., analog signal conditioning, switchingfunctions, and/or digital logic controls) in accordance with a pathbetween contacts (e.g., short, open, or resistance) or a signalappearing on or between contacts (e.g., logic high, logic low, data wordreceived in true or complement form, a meaningful signal amplitude,frequency, or modulation).

By detecting one or more paths and/or signals completed by theterminator, a code may be determined for use in controlling thesubsystem's circuit functions or software functions. Becauseconventional data ports provide signals from which hundreds ofalternative codes may be designed, the invention has wide practicalapplication.

When such a terminator replaces a conventional dust cover for the port,and the terminator is designed to include a minimum number of shortcircuit paths, enhanced operation of the avionics is realized with nochange in cockpit wiring and with little additional cost for hardwareand hardware support (e.g., depot inventory).

BRIEF DESCRIPTION OF THE DRAWING

Embodiments of the present invention will now be further described withreference to the drawing, wherein like designations denote likeelements, and:

FIG. 1 is a functional block diagram of a system according to variousaspects of the present invention;

FIG. 2A is a partial schematic diagram of a data loader connected to asubsystem according to conventional techniques;

FIG. 2B is a partial schematic diagram of a terminator connected to asubsystem according to various aspects of the present invention;

FIG. 3 is a functional block diagram of a traffic collision avoidancesystem according to various aspects of the present invention; and

FIG. 4 is a process flow diagram of a method for configuring a functionof a transponder in the system of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In systems according to various aspects of the present invention, asubsystem (e.g., a line replaceable unit (LRU) of an avionics system)has a port used in at least two modes of operation. In a first mode,software is accepted for in situ installation. When the port comprises aconnector, a cable is connected to the connector and to a source ofsignals used to convey the software into the port. In a second mode, aterminator at the port provides configuration information for use by theinstalled software. When the port comprises a connector, a first circuitin the subsystem is coupled to a second circuit in the terminator (e.g.,a code plug, or a circuit installed in a dust cover) as the terminatoris connected to the connector. In one implementation, the circuit of theterminator shorts particular contacts of the connector to conveyconfiguration information.

For example, system 100 of FIG. 1 generally illustrates a systemarchitecture according to various aspects of the present invention.System 100 is typically installed in a vehicle (e.g., an aircraft, landvehicle, space vehicle, ship, or submarine). System 100 may perform anyvehicular control function, operator decision support function, payloadoperation function, or passenger entertainment function. System 100includes subsystems 102, 104, and 106 each of which is mechanically andelectrically installed at an interface 114. Interface 114 may includerack mount structures for holding subsystems in relative position duringuse of the vehicle. Interface 114 is designed to permit removal andreplacement of one or more subsystems for maintenance or repair of thesubsystem. Interconnecting cables for power, analog signals, and digitalsignals are somewhat permanently installed on the interconnection sideof interface 114 while subsystems are installed and operated from theoperation side of interface 114. Interface 114 may include bays or traysfacilitating subsystem installation and removal. For example, system 100includes tray 110. A tray provides mechanical support for a subsystem orfor connections at interface 114. A tray may also include memory read bythe subsystem for directing operation of a subsystem.

The interconnection side of interface 114 includes cables 142, and 146.Cable 142 has a connector 141 to subsystem 102 receptacle J1 and aconnector 143 to subsystem 104 receptacle J1. Cable 146 has a connector145 to subsystem 104 receptacle J3 and a connector 147 to subsystem 106receptacle J1. Environment memory 112 of tray 110 is accessed viaconnector 144 to subsystem 104 receptacle J2. Conventional code plug 152is connected somewhat permanently to subsystem 106 receptacle J2. Inoperation, conventional circuits of subsystem 106 read theinterconnections among receptacle contacts of J2 to govern at least aportion of the operation of subsystem 106.

Subsystems 102 and 104 each include a port used in two modes ofoperation, as discussed above. On subsystem 102, front panel receptacleJ2 provides such a port. On subsystem 104, front panel receptacle J4provides such a port. As shown, subsystem 102 is prepared to performvehicular operations as discussed above (e.g., in a normal mode ofoperation of system 100). Also as shown, software is being installedinto subsystem 104 via receptacle J4. After installation of software,data loader 108 and cable 162 are removed and subsystem 104 receptacleJ4 is covered with a terminator of the type discussed below withreference to 170.

A conventional data loader provides signaling protocol and data frommedia mounted in or on the data loader to an interface for connection toa subsystem. For example, data loader 108 includes a conventional dataloader of the type described in ARINC specifications and reports of the603, 614, and 615 families available from Aeronautical Radio, Inc. Dataloader 108 is connected by cable 162 to subsystem 104 receptacle J4 forcopying software from media mounted on data loader 108 (e.g., CD-ROM) toa memory (e.g., magnetic or optical disk, semiconductor RAM, FLASH, orEPROM) in subsystem 104. Cable 162 includes connector 161 connected tosubsystem 104 receptacle J4 and connector 163 connected to data loader108. In one implementation, data loader 108 may be connected tosubsystem 102 at J2 using the same or a different cable 162. Data fromdata loader 108 may be stored through a subsystem into environmentmemory. For example, either subsystem 104 or data loader 108 may storedata in environment memory 112.

Data loading is facilitated by interface circuits of the data loader,connecting cable, and subsystem. For example, interface circuits of dataloader 108, cable assembly 162, and subsystem 104 of FIG. 2A includeconventional differential line receivers, conventional differential linedrivers, and conventional discrete line receivers. Data loader 108includes any number of line receivers 202 (e.g., LR1), typically one foreach ARINC 429 bus line used to receive data (e.g., status and controlsignals) into data loader 108. Data loader 108 includes any number ofline drivers 204 (e.g., LD2), typically one for each ARINC 429 bus lineused to transmit data (e.g., software for a subsystem memory) intosubsystem 104. Data loader 108 may further include one or more switches206 (e.g., front panel switch S1 for use by an operator of data loader108) for manually setting conventional discrete inputs of subsystem 104;and may include one or more links 208 used conventionally forautomatically determining that a cable (e.g., 162) has been connected tosubsystem 104 in preparation for data loading. Chassis and groundsignals (e.g., for safety, limiting electrical interference, andproviding reference potentials) are coupled between data loader 108 andsubsystem 104 via shields (e.g., contacts 5 and 16), and via dedicatedconductors (e.g., contact 21).

A subsystem includes interface circuits for cooperating with the dataloading functions. For example, subsystem 104 includes any number ofline drivers 212 (e.g., LD1), typically one for each ARINC 429 bus lineused to transmit data (e.g., status and control signals) from subsystem104. Subsystem 104 includes any number of line receivers 214 (e.g.,LR2), typically one for each ARINC 429 bus line used to receive data(e.g., software for a subsystem memory) into subsystem 104. Subsystem104 may further include one or more line receivers 216 and 218 forsensing conventional discrete inputs of subsystem 104 (e.g., manuallyset switch positions, or relay contact closures) and sensing one or morelinks 208.

According to various aspects of the present invention, a terminator fora data loader port of a subsystem indicates information for subsystemoperation. In one implementation, the terminator completes a circuit ofthe subsystem. For example, subsystems 102 and 104 include circuits eachcomprising a receptacle J2 and J4 respectively used in turn with a dataloader 108. Terminator 170 provides a termination for data loader portJ2 of subsystem 102 and completes a circuit of subsystem 102. When aterminator completes a circuit of a subsystem, the circuit may controlany aspect of subsystem operation according to the terminator. Forexample, a terminator may provide a code readable by software of thesubsystem. Such a code may be used directly or as an identifier of otherinformation (e.g., an indirect reference, parameter name, or index) tobe used in operation of the subsystem (e.g., an address, or pointer). Aterminator may function in a circuit to select a mode of operation,identify a table of parametric values, determine a parametric value,operate a logic circuit, operate a relay circuit, or operate a switchingcircuit. The circuitry of a terminator used with subsystem 102 may bedifferent from the circuitry of the terminator used with subsystem 104.

For example, terminator 270 of FIG. 2B includes a connector P1 and acircuit 260 that cooperates with circuits of subsystem 104 discussedabove with reference to FIG. 2A. Circuit 260 includes conductors 272 and274 that complete a path between LD1 and LR2; conductor 276 thatcompletes a path that grounds a discrete input into DR1 and conductor278 that completes a path that grounds a link detection circuit DR2. Inalternate implementations any number of any of these three types ofpaths may be used. A large number of configuration codes may be providedby alternative circuits 260. For example, when four discrete inputs areincluded in subsystem 104 (e.g., J4 contacts 50, 51, 52 and 53), andeach discrete input can have one of two states (e.g., open or grounded),any one of 2⁴ or sixteen codes may be implemented using discrete inputsand paths to ground. As another example, when four output buses (e.g.,J4 contacts 8 through 15) and two input buses (e.g., J4 contacts 1through 4) are included in subsystem 104, and each input can have one offive states, any one of 5⁴ or 625 codes may be implemented using pathsbetween buses. The five states of an input bus may include open, coupledto the first output bus, coupled to the second output bus, inverselycoupled to the first output bus, and inversely coupled to the secondoutput bus. In an inverse coupling, a conductor (e.g., 272), connects apositive output (e.g., of LD1) to a negative input (e.g., of LR2). Whenbus paths and discrete input paths are combined, any one of up to 10,000codes may be implemented in a terminator 270.

Terminator 270 as discussed above is preferred for simplicity,reliability, and low manufacturing costs. Terminator 270 cooperates withcircuitry already part of subsystem 104 that is otherwise used for dataloading functions. In other words, terminators according to variousaspects of the present invention may be implemented with no additionalcircuitry in a subsystem specific to a terminator. Conventional softwaretechniques may be performed by a processor of subsystem 104 to determinewhat if any paths are formed by terminator 270 and then put into effecta desired configuration corresponding to the terminator circuitry (e.g.,corresponding to a code implemented by terminator circuitry 260).

In alternate implementations, the circuitry of a subsystem mayincorporate the contacts of a data port receptacle to perform anymodification of circuit functions (e.g., analog signal conditioning,switching functions, and/or digital logic controls) in accordance with apath between contacts (e.g., short, open, or resistance) or a signalappearing on or between contacts (e.g., logic high, logic low, data wordreceived in true or complement form, a meaningful signal amplitude,frequency, or modulation). Such alternate circuitry may include aregister for reading path completion logic signals in parallel, ananalog to digital converter for reading the value of a resistancebetween contacts, control circuits (e.g., relay drivers, multiplexors,gates, or electronic switches) that respond to signals coupled via pathsformed by terminator circuitry, or signal sources (e.g., unique or outof band signaling such as over voltage, unused frequencies, or specialmodulations) used through paths of the terminator to operate subsystemcircuitry in ways detectable for configuration control or that implementconfiguration alternatives of the subsystem.

Terminator 270 includes circuit paths for any conventional signal. Forexample, paths 272-278 each conduct digital signals and in an alternateimplementation may conduct a broadband analog, pulsed digital, ormodulated signal.

Terminator 270 may be assembled using any conventional connector (e.g.,a plug with a back shell or cap) and potting compound to provideenvironmental protection for circuitry 260. In a preferredimplementation, terminator 270 is tethered to the front panel ofsubsystem 104 for use exclusively with connector J4 of subsystem 104.

In an implementation where interfaces employ optical signaling, the dataport and terminator include any conventional techniques for establishingpassive paths. For example, a wide or narrow bandwidth path with orwithout polarization and/or filtering may be implemented using opticfiber, refractors, reflectors, dividers, combiners, and conventionalfiltering materials and coatings.

An avionics system, according to various aspects of the presentinvention, performs a collision avoidance process in accordance withsoftware loaded via a port and in accordance with a circuit of aterminator coupled to the port. For example, avionics system 300 of FIG.3 includes a rack mounting interface 314 (e.g., of the type described inARINC 600) for mounting a plurality of subsystems securely in anaircraft and removably for individual subsystem repair and/or upgrade.Subsystems include a control panel 302, two transponders 304 and 306, acollision avoidance system processor 308 (e.g., of the type described asa TCAS in DO-185A “Minimum Operational Performance Standards for TrafficAlert and Collision Avoidance System II (TCAS II)” available from RTCAInc.), an altimeter 310, and a display 312.

The installation side of interface 314 includes cables, antennas, andenvironment memory. For transponder status and control, cables 322 and324 connect control panel 302 to transponders 304 and 306. Fortransponder cooperation with CAS processing, cables 326 and 328 connecttransponders 304 and 306 to CAS processor 308. Each transponder isconnected to two antennas for transmitting and receiving respectively:antennas 252 and 254 for transponder 304 and antennas 356 and 358 fortransponder 306. CAS processor 308 includes a transponder coupled toantennas 362 and 364 for transmitting and receiving respectively.Environment memory 316 is connected to CAS processor 306 and containsconventional configuration information, for example, describing theaircraft on which system 300 is installed. Altimeter 310 is connected toCAS processor 308 by cable 330. And, display 312 is connected to CASprocessor 308 by cable 332.

System 300 provides traffic advisories and resolution advisories in anyconventional manner, for example, as described in DO-185A. Further,transponders of system 300 provide redundancy and cooperate in a normalmode and in a hijack mode. In a hijack mode, each transponder (304 or306) performs a method, according to various aspects of the presentinvention, for maintaining transponder and/or TCAS functions.

For example, a method of transponding performed by transponder 304(e.g., and by 306) includes a method 400 of FIG. 4 for maintainingtransponder operations. To begin, it is determined (402) whethertransponder 304 is currently operating (or commanded to operate) in ahijack mode of operation; and, if not, then no further action is takenin method 400. Otherwise, the present operating configuration oftransponder 304 is determined (404). Determining the present operatingconfiguration includes detecting the presence of a terminator of thetype described above with reference to terminator 270. If present,determination of configuration further includes detecting directly orindirectly any attributes of circuitry of the terminator (260) includingany modification of circuit functions, paths, and/or signal.Collectively, the combination of modification of circuit functions,paths, and/or information conveyed by signals is referred to herein as aconfiguration. The determination (404) provides indicia of configurationthat may be analyzed and used for decisions of method 400. For example,whether or not transponder 304 is currently operating with an antennathat is shared with another function (e.g., another transponder) isdetermined (406) by testing directly or indirectly the indicia ofconfiguration. An indirect test may include a test on a result of usingsome or all of the indicia (e.g., a code or value) in an algorithmicexpression (e.g., bit mask) or in a table look up as discussed above. Ifa shared antenna is being used, the transponder continues operating inan active mode (e.g., assures that it is in an active mode and changesto an active mode if necessary). Transponder 304 (and 306) may operatenormally in an active mode as opposed to a standby mode as specified,for example, by a pilot-operated switch on control panel 302 inaccordance with industry standards and reports in families 718 and 735.Industry standards include standards, specifications, andrecommendations for any transportation industry: military or civilian(e.g., aviation, land vehicles, ships and submarines, space craft). Forexample, suitable industry standards include publications by ARINC, RTCAInc., Air Transport Association, Federal Aviation Administration,Society of Automotive Engineers, Federal Communications Commission,Institute of Electrical and Electronic Engineering, American NationalStandards Institute, National Institute of Standards and Technology,Computer and Communications Industry Association, InternationalTelecommunication Union, International Technical Commission,International Standards Organization, and Electrical IndustryAssociation. Mode change (408) is avoided when no shared antenna isbeing used (406). Finally, further mode change signals (if any) areignored for purposes of effecting a mode change. For example, if apilot-operated switch on control panel 302 is set in an attempt to placetransponder 304 in a standby (e.g., non-transmitting) mode, transponder304 remains in an active mode (e.g., transmitting squitters and/orresponses to interrogations).

The foregoing description discusses preferred embodiments of the presentinvention which may be changed or modified without departing from thescope of the present invention as defined in the claims. While for thesake of clarity of description, several specific embodiments of theinvention have been described, the scope of the invention is intended tobe measured by the claims as set forth below.

1. A system comprising: a plurality of subsystems coupled at a firstinterface for communication of signals among subsystems, wherein atleast one particular subsystem comprises: a second interface comprisinga port for receiving software; and a first circuit coupled to the port;and a terminator coupled to the port when the port is not receivingsoftware, the terminator comprising a second circuit coupled to thefirst circuit, wherein a function of the subsystem is performed inaccordance with the first circuit and the second circuit, wherein thesystem is installed on a host aircraft to perform a collision avoidancefunction and further comprises: a transponder for collision avoidancesignaling in accordance with operation of the first circuit and thesecond circuit; and a plurality of antennas coupled to the transponderfor collision avoidance signaling, and a particular antenna providingthe collision avoidance signaling in accordance with operation of thefirst circuit and the second circuit.
 2. The system of claim 1 whereinthe second interface further comprises at least one of a controloperated by an operator of the system and a display viewed by anoperator of the system.
 3. The system of claim 1 wherein the firstcircuit comprises logic and the second circuit provides a logic signalto the logic.
 4. The system of claim 3 wherein the logic comprisesdigital logic components.
 5. The system of claim 3 wherein the logiccomprises a relay.
 6. The system of claim 1 wherein the particularsubsystem comprises a transponder.
 7. The system of claim 1 wherein theparticular subsystem comprises a TCAS processor.
 8. The system of claim1 wherein the port is operable according to an industry standard.
 9. Amethod for operating a replaceable unit of an avionics system, themethod comprising: receiving, in a first mode of operation, software viaa port; and operating, in a second mode of operation, in accordance witha circuit comprising a terminator coupled to the port.
 10. The method ofclaim 9 wherein operating in the second mode of operation comprisesconfiguring one or more aspects of the system.
 11. The method of claim 9wherein operating in the second mode of operating comprises configuringone or more aspects of the software.
 12. A method of operating atransponder with a hijack mode of operation, the method comprising:providing a signal indicating an initiation of the hijack mode ofoperation; and preventing the disabling of the transponder following theinitiation of the hijack mode of operation.
 13. A system for operating areplaceable unit of an avionics system, the system comprising: receivingmeans for receiving, in a first mode of operation, software via a port;and operating means for operating, in a second mode of operation, inaccordance with a circuit comprising a terminator coupled to the port.14. The system of claim 13 wherein operating in the second mode ofoperation comprises configuring one or more aspects of the system. 15.The system of claim 13 wherein operating in the second mode of operatingcomprises configuring one or more aspects of the software.
 16. A systemof operating a transponder with a hijack mode of operation, the systemcomprising: providing means for providing a signal indicating aninitiation of the hijack mode of operation; and preventing means forpreventing the disabling of the transponder following the initiation ofthe hijack mode of operation.